Hello @ZenMusic2
Option is indeed to use MobiFlight. This is a great tool which offers a lot of flexibility. And the nice thing about MobiFlight is that you don’t need to know anything about coding. It is completely configurable. And on top of that, there is a lot of information found on the internet. I have used MobiFlight in the beginning and learned a lot from it.
But if you really want to experiment with my approach, then I suggest you to go to my other post that contains a next iteration. Tool to connect Serial USB devices to MSFS2020 via SimConnect/WASM using VS2022 - Community Support / Home Cockpit Builders - Microsoft Flight Simulator Forums . I use this tool myself, and already successfully connected it with my PIC-microcontroller driven FCU and MCDU for the FBW A32NX. This tool is used by some other people with success, and according to some feedback it seems pretty stable (some call it “rock solid” 
). So far, I haven’t found a single bug since I launched it 
.
Finding the correct commands/variables is indeed always a struggle. @DeadCertainty gave a good advice to have a look on HubHop. But depending on the airplane you are using, internet provides a lot of useful information. But it’s a struggle sometimes, because there is not a single consistent source that has it all. I call it “part of the fun”. One advice I can give you is to use the execute_calculator_code function in the WASM module, because that is sometimes an easy escape as it accepts all types of variables. For example, I needed to control “H”-variables, and had no clue how to do that. But I simply used the execute_calculator_code, and it works as a charm (all keypresses for my MCDU work like that).
And recently, I have been experimenting with Chat-GPT. I have the feeling that this will create a lot of new possibilities. As an example, I asked it to explain me some complex RPN code string, and it gave me a very good analysis. It even realized that the code was related to MSFS, and it could even identify in what part of the plane this was used. Really amazing!